[1,of,3] cx88: Add support for stereo and sap detection for A2

Commit Message

Marton Balint April 6, 2009, 12:36 a.m. UTC

On Sun, 5 Apr 2009, Mauro Carvalho Chehab wrote:

> Hi Marton,
> 
> I suspect that you will need to use div64 math or some othe way to calculate the freq:
> 
> /home/v4l/master/v4l/cx88-dsp.c: In function 'detect_a2_a2m_eiaj':
> /home/v4l/master/v4l/cx88-dsp.c:147: error: SSE register return with SSE disabled
> make[3]: *** [/home/v4l/master/v4l/cx88-dsp.o] Error 1
> make[3]: *** Waiting for unfinished jobs....

Gcc should have optimised away the floating point operations and the 
__builtin_remainder function. Hmm, it seems that older gcc's don't do 
this. Would you try the attached patch? It uses integer modulo instead 
of __builtin_remainder, so only basic floating point operations needs 
optimising, hopefully every common gcc version will be able to do it.

Regards,
  Marton

# HG changeset patch
# User Marton Balint <[e-mail]>
# Date 1238977280 -7200
# Node ID 5a396f71d463b738c363c12bf53a3e446016aa95
# Parent  119acaa1dee387960325ba637c6257af2b0fd3af
cx88: dsp: more gcc compatible remainder function

From: Marton Balint <[e-mail]>

Priority: normal

Signed-off-by: Marton Balint <[e-mail]>

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Comments

Mauro Carvalho Chehab April 6, 2009, 1:23 a.m. UTC | #1

On Mon, 6 Apr 2009 02:36:01 +0200 (CEST)
Marton Balint <[e-mail]> wrote:

> On Sun, 5 Apr 2009, Mauro Carvalho Chehab wrote:
> 
> > Hi Marton,
> > 
> > I suspect that you will need to use div64 math or some othe way to calculate the freq:
> > 
> > /home/v4l/master/v4l/cx88-dsp.c: In function 'detect_a2_a2m_eiaj':
> > /home/v4l/master/v4l/cx88-dsp.c:147: error: SSE register return with SSE disabled
> > make[3]: *** [/home/v4l/master/v4l/cx88-dsp.o] Error 1
> > make[3]: *** Waiting for unfinished jobs....
> 
> Gcc should have optimised away the floating point operations and the 
> __builtin_remainder function. Hmm, it seems that older gcc's don't do 
> this. Would you try the attached patch? It uses integer modulo instead 
> of __builtin_remainder, so only basic floating point operations needs 
> optimising, hopefully every common gcc version will be able to do it.

Worked. I've folded this patch with the previous one, to avoid bisect breakage upstream.

Cheers,
Mauro
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Patch

diff -r 119acaa1dee3 -r 5a396f71d463 linux/drivers/media/video/cx88/cx88-dsp.c
--- a/linux/drivers/media/video/cx88/cx88-dsp.c	Tue Mar 31 23:35:57 2009 +0200
+++ b/linux/drivers/media/video/cx88/cx88-dsp.c	Mon Apr 06 02:21:20 2009 +0200
@@ -28,8 +28,11 @@ 
 
 #define INT_PI			((s32)(3.141592653589 * 32768.0))
 
+#define compat_remainder(a, b) \
+	 ((float)(((s32)((a)*100))%((s32)((b)*100)))/100.0)
+
 #define baseband_freq(carrier, srate, tone) ((s32)( \
-	 (__builtin_remainder(carrier + tone, srate)) / srate * 2 * INT_PI))
+	 (compat_remainder(carrier + tone, srate)) / srate * 2 * INT_PI))
 
 /* We calculate the baseband frequencies of the carrier and the pilot tones
  * based on the the sampling rate of the audio rds fifo. */